Bridget Jones fans, take heart: The plucky, hilarious heroine is poised to make her return.

The wine-guzzling, weight-checking, big undies-sporting star of the 1996 smash novel Bridget Jones's Diary and its 1999 sequel – both brought to life on film by Renée Zellweger – is "just turning 40," says author Helen Fielding, who is currently writing the third book in the series.

"Bridget is struggling with baby issues – that sort of baby panic," Fielding tells PEOPLE. "It's going to be talking about babies and life and really the theme of it is expectation: the way life never turns out quite the way you expect."

Haul out the biscuits and gravy, crispy duck, Snickers, milk shakes, pizza and butter-soaked potatoes – Renée Zellweger's very special diet to get in shape to play Bridget Jones, because the Oscar winner is prepping to play the full-figured singleton once again.

Zellweger, 40, is expected to start filming at the end of this year what will be the third installment about the love-starved British publishing executive, Variety reports.

This time, the story will likely focus on 40-ish Bridget's desire to have a baby before time runs out, as based on author Helen Fielding's weekly newspaper columns for Britain's The Independent, says the showbiz trade publication.